Home/Species/ Railhead Milkvetch

Astragalus terminalis

S. Wats.

Railhead Milkvetch

G3Vulnerable Found in 4 roadless areas NatureServe Explorer →

G3VulnerableGlobal Rank

Least concernIUCN

Identity

Unique IDELEMENT_GLOBAL.2.130492

Element CodePDFAB0F8U0

Record TypeSPECIES

ClassificationSpecies

Classification StatusStandard

Name CategoryVascular Plant

IUCNLeast concern

Endemicendemic to a single nation

KingdomPlantae

PhylumAnthophyta

ClassDicotyledoneae

OrderFabales

FamilyFabaceae

GenusAstragalus

Concept Reference

Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

Conservation Status

Review Date2011-06-10

Change Date1998-02-01

Edition Date1999-12-28

Edition AuthorsFertig, W. and B. Heidel 12-99.

Range Extent250-2,500,000 square km (about 100-1,000,000 square miles)

Number of Occurrences6 - 80

Rank Reasons

Astragalus terminalis is geographically restricted; known from east-central Idaho, north to southwestern Montana and south to western Wyoming. In Montana, the plant is known from more than a dozen sites in Beaverhead and Madison Counties, and in Wyoming the plant is known from only five extant occurrences. Four Wyoming populations are protected in Grand Teton National Park and the National Elk Refuge. Populations outside of protected areas in Wyoming may be threatened by gravel quarrying, grazing, and invasive weeds. Some sites in Montana may be adversely impacted by grazing activities and invasives weeds. The status of the species in Idaho is unclear.

Range Extent Comments

Railhead milkvetch is a regional endemic of central Idaho, southwestern Montana, and northwestern Wyoming.

Occurrences Comments

11 extant and 3 historical occurrences in Montana, 5 extant and 2 historical occurrences in Wyoming, undetermined number in Idaho.

Threat Impact Comments

The species is threatened by grazing, subdivision, and weed invasion in some of the low elevation populations in Montana, and potentially by gravel quarrying in Wyoming.

Ecology & Habitat

Description

Railhead milkvetch is a tufted, taprooted perennial herb with several erect stems that reach 5-30 cm in height. The pinnately compound leaves are 5-20 cm long and have 13-21 oblong leaflets with blunt tips. Foliage is sparsely covered with forked gray hairs that branch at the base and spread in opposite directions and are appressed to the surface of leaves or stem. Dense clusters of 10-30 flowers are borne in the axils of upper leaves and become less crowded as the plant matures. The white, pea-like corollas are 12-16 mm long, with the upper petal reflexed and the lower petal purple-spotted. The calyx reaches 4-5 mm and is covered with white or black hairs. The cigar-shaped fruits are glabrous, unstalked, 3-sided in cross-section, and 15-20 mm long. The alpine ecotype is much smaller than plants from the valleys.

Diagnostic Characteristics

A. TERMINALIS is similar to A. SCAPHOIDES and A. ATROPUBESCENS, but can be distinguished by the nearly sessile fruits, while fruits of the other 2 species have stalks that are 3-20 mm long.

Habitat

Sagebrush steppe and sparsely-vegetated grasslands in the valley, foothills, montane, and alpine zones; 1524-2914 m (Montana Natural Heritage Program 1999).

Terrestrial Habitats

Grassland/herbaceousAlpine

Other Nations (1)

United StatesN3

Province	Rank	Native
Idaho	SNR	Yes
Wyoming	S2	Yes
Montana	S2	Yes

Plant Characteristics

Economic Value (Genus)Yes

Roadless Areas (4)

Montana (2)

Area	Forest	Acres
Big Horn Mountain	Beaverhead-Deerlodge National Forest	50,846
Snowcrest Mountain	Beaverhead-Deerlodge National Forest	97,649

Wyoming (2)

Area	Forest	Acres
Gros Ventre Mountains	Bridger-Teton National Forest	106,418
Spread Creek - Gros Ventre River	Bridger-Teton National Forest	166,097

References (8)

Culver, D. R. 1993. Sensitive plant species inventory in the Centennial Valley, Beaverhead County, Montana. Unpublished report to the Butte District, Bureau of Land Management. Montana Natural Heritage Program, Helena, 42 pp. plus appendices.
Fertig, Walter. Personal communication. Former botanist. Wyoming Natural Diversity Database, University of Wyoming, Laramie, WY
Isely, D. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States (exclusive of Alaska and Hawaii). Monte L. Bean Life Science Museum, Brigham Young University; MLBM Press, Provo, Utah. 1007 pp.
Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Lesica, P., G. Moore, K.M. Peterson, and J.H. Rumely. 1984. Vascular plants of limited distribution in Montana. Montana Academy of Sciences, Supplement to the Proceedings 43(2):1-61.
Montana Natural Heritage Program. 1999. April 1 - last update. Species Information: Astragalus terminalis. Montana Natural Heritage Program. Online. Available: http://orion2.nris.state.mt.us/mtnhp/plants/index.html Accessed 1999, April 14.
Vanderhorst, J. 1995a. Sensitive plant survey in the Horse Prairie Creek drainage, Beaverhead County, Montana. Unpublished report to the Bureau of Land Management, Butte District. Montana Natural Heritage Program, Helena, Montana. 42 pp. plus appendices.
Vanderhorst, J. P. and P. Lesica. 1994. Sensitive plant survey in the Tendoy Mountains, Beaverhead County, Montana. Unpublished report to the Bureau of Land Management, Butte District. Montana Natural Heritage Program, Helena, MT. 59 pp. plus appendices.